the arteries as the second; the capillary vessels
as the third; and the veins as the fourth. To
view each arc distinctly, as well as the whole
circle connectedly, will greatly assist us in forming
accurate views of the nature of the circulation.
Galen, of whom Harvey speaks as “ viri divini,
patris medicorum,” appears to have been the first
to have a distinct view of the circulation,—the first
to have reasoned correctly upon a view of part of
the valvular structure of the heart. He uses the following
words, which will be regarded as remarkable,
considering the remote period at -which they
were written: “ Est mutua anastomosis atque os-
cillorum apertio, arteriis simul cum venis ; transum-
untque ex sese pariter sanguinem et spiritunq per
invisibiles quasdam atque augustas plane vias. Quod
si os ipsum vense arteriosse itidem semper patu-
isset, nullamque natura invenisset machinam, quae
claudere ipsum, cum est tempestivum, ac rursus
aperire queat ; fieri nunquam potuisset ut per
invisibilia atque exigua oscilla sanguis (contracto
thorace) in arterias transumeretur : neque enim
similiter omnis ex quovis attrahitur, neque emit-
titur. Sed quemadmodum quod leve est, facilius
eo quod gravius, dilatatis instrumentis, attrahitur,
iisdem autem contractis exprimitur : ita et per
latam viam celerius aliquid quam per angustam
trahitur, ac rursus emittitur. Cum autem thorax
contrahitur, pulsæ atque intro compressæ undique,
quæ in pulmone sunt, venosæ arteriæ, expri-
munt quidem quam celerrime, qui in ipsis est,
spiritum ; transumunt autem per subtilia ilia oscilla
sanguinis portionem aliquam ; quod nunquam
accidisset profecto, si sanguis per maximum
os (cujusmodi est venæ arteriosæ) ad cor retro
remeare potuisset. Nunc vero reditu per os magnum
intercluso, dum comprimitur undique, distillât
quidpiam in arterias per exigua ilia ori-
ficia.” 1 “ Nisi valvulæ essent, triplex sequeretur in-
commodum, ut sanguis ipse frustra longum hoc
Curriculum subinde emetiatur ; in diastolis quidem
pulmonis adfiuens, et quæ in ipso sunt venas
omnes referciens ; in systolis vero, quasi æstus
quidem maritimus instar Euripi, motum iden-
tidem hue atque illuc reciprocans, qui haudqua-
quam sanguin! conveniat.” 2
But to Harvey is due the honor of having
clearly demonstrated the entire circulation ; and
the no less honor of having set us an early
* Galen de Usu Partiuin, Lib. vi. Cap. x. 2 Ibid.